This invention relates to hollow dishes, preferably hollow metal and plastic dishes such as plates, having discrete, meltable cores, preferably wax cores, sealed within an oxygen- and water-free cavity inside the hollow dishes. This invention also relates to a method of making such hollow dishes.
Our new hollow dishes with discrete, meltable cores, preferably wax cores, preferably include a top member, a complementary bottom member, and means at the peripheries of each for joining them to one another at their peripheries to form a hollow cavity between them. The hollow cavity so formed is substantially impermeable to water and air or other oxygen-containing gases. As a result, the meltable core inside the sealed cavity is insulated from oxidation, water damage and other kinds of degradation.
Our method for making the new hollow dishes with discrete, meltable cores, preferably wax cores, comprises liquifying a meltable substance such as wax in an oxygen-free, inert atmosphere; cooling and solidifying the meltable substance to form a solid, meltable core for such dishes; placing the solid meltable core inside the hollow dish; removing or otherwise excluding substantially all oxygen from the core-containing cavity inside the hollow dish; and sealing the core inside the hollow dish. Such sealing precludes escape of the meltable core from its cavity, and prevents air, oxygen-containing gases, water and other contaminants from entering the cavity and attacking the core.
In the preferred embodiment of our new hollow dishes, the hollow dishes include two members, preferably made of a metal such as stainless steel. The upper member and lower member are complementary in size and shape, and include means for sealing them to one another (preferably at their peripheries) to form a hollow, sealed cavity between them. Alternatively, the hollow dish may be of one-piece or other construction or of other materials such as thermoplastic and thermoset materials. Such dishes must includes means (such as a filling hole) for placing a meltable core substance inside them. Though our invention relates to dishes of many different sizes, e.g., round, elliptical, square, our preferred embodiment is a plate, especially a round or square metal plate.
The meltable core is preferably made of an asphalt substance, or a wax with high specific heat and a melting point in the range of about 180.degree. F. to about 215.degree. F., such as synthetic, hardened microcrystalline wax, carnauba wax, Cornowax or slack wax. Such substances store a large quantity of heat energy that is gradually released at a rate slower than the rate at which the heat was stored. When molding the wax to a shape suitable for insertion into the core of a hollow dish such as a plate, our process calls for melting, then solidifying the wax in an appropriately shaped mold or die while excluding air, other oxygen-containing gases, water, and other contaminants from the core.